1. Field of the Invention
This invention relates generally to the removal of foreign objects or contaminents from tubular structures and more particularly to an apparatus and method ideally suited by simultaneously cleansing and removing water from the interior of a waveguide.
2. Description of the Prior Art
Tubular structures, such as waveguides, conduits or pipelines, when damaged, can collect or become clogged with foreign objects, which often impede the normal function of the structure even if the damage is repaired. These contaminents or obstructions must be removed before normal operation of the structure can be resumed. In some instances, mechanical scraping devices have been employed to clear out blockages. A metal wire connected to the scraping device is often used as a means of remotely controlling the insertion of the scraping apparatus. However, the lack of stiffness of the wire limits the distance that the operator can push the scraping mechanism into the tubular structure. In addition, scraping devices are often unsatisfactory where the structures to be cleaned are delicate or susceptible to internal damage. In the case of the waveguide, water which enters upon accidental rupture may be the "foreign object"; such water causes contamination to the waveguide and severely attenuates energy modes traveling throughout the structure. While collected water cannot be removed by scraping devices, another prior art technique, known as "pigging", can be used. Specifically, the "pig" is inserted into the waveguide and blown through by an external force, usually compressed air. However, since no mechanical link is maintained between the device and the operator, the position of the pig within the structure is difficult to control remotely. The pig must travel the entire length of the waveguide before removal, causing additional contamination to occur. Also, because the pig must be inserted at one place and retrieved at another often miles apart, time loss, resulting in additional unnecessary damage to the structure, cannot be avoided.
Another prior art cleaning arrangement consists of a plurality of scraper and brush type elements mounted upon a central body which propagates through the tubular structure in manner corresponding to the above-described pig. A self-contained gas charge, or similar means, is employed to govern the pressure exerted upon the walls of the conduit by the cleaning elements. While this arrangement may be advantageous in some instances, numerous problems nevertheless remain. Primarily, complexity in the design of such devices results in high manufacturing cost as well as a greater chance of malfunction. Secondly, as with the pigging technique, the position of the device within the tubular structure is difficult to control remotely as no mechanical link exists between the apparatus and the operator. Thirdly, these devices are not able to introduce cleaning fluids from an external source into the apparatus, to be used to wash the walls of tubular structure as the obstruction is being removed.
In view of the foregoing discussion, it is a broad object of the present invention to provide an improved method and apparatus for cleaning tubular structures, where cleaning includes the removal of foreign ofjects or fluids lodged or collected within the structure. Specific objects include increasing insertion distance of the device into the tubular structure, conveniently and reliably controlling the position of the device in the tubular structure, and simplifying the overall design and construction of the device while yet permitting the introduction of a cleaning substance into the device.